The tracer ratio method serves to quantify emissions in naturally ventilated animal housing systems. Empa and Agroscope have developed a tracer ratio method with two tracer gases for comparative emission measurements in Agroscope’s experimental dairy housing, with its two spatially separated compartments. In this method, the tracer gases sulphur hexafluoride (SF6) and trifluoromethyl sulphur pentafluoride (SF5CF3) are continously dosed near to the floors via a tube system with critical capillaries, thus representing the emission sources. Spatially distributed sampling is performed via air manifolds and critical capillaries. Tracer and target gases are then analysed and the emissions calculated. Systematic validation trials show that both tracer gases behave equivalently. The dosing and sampling scheme allows emissions to be determined for both areal and point sources. In addition, the two different tracer gases can be used to detect and quantify any possible gas transport between the two housing compartments. Consequently, the tracer ratio method is suitable for the comparative determination of the emission-reduction potential of abatement measures.
Validation of the tracer ratio method for emission measurements in naturally ventilated housing